Computed tomography (CT) is a technology that makes use of computer-processed combinations of X-ray projections taken from different angles to produce cross-sectional images. The CT technology has been widely used in medical diagnosis. During a reconstruction process of a CT image, artifacts (e.g., staircase artifacts) may appear on tissue boundaries. The artifacts may reduce the image quality and influence the results of diagnosis on the basis of such an image. It is desirable to provide systems and methods for reconstructing a CT image with improved quality and reduced artifacts.